A numerical simulation study on the CO2 leakage through the fault

Many carbon capture and storage projects are underway all over the world to reduce greenhouse gas emissions. In this study, we numerically analyze the movement of injected CO₂ through the faults undetected prior to injection. We use TOUGH2-MP ECO2N software to estimate the behavior of injected and leaked CO₂. The storage site is 100 m thick saline aquifer located 850 m under the shallow continental shelf. It is assumed that CO₂ is first leaked through the 1^st fault located 400 m away from injection well and then leaked to the seabed through the 2^nd fault located 400 m away from 1^st fault. We vary the injection rate of CO₂ to 0.25, 0.50, and 0.75 MtCO2/year to analyze the effect of injection rate. For 0.25 MtCO₂/year injection rate, no leakage is calculated, however, for 0.50 and 0.75 MtCO₂/year, the leakages of CO₂ to seabed are detected. The starting times of leakage at 0.5 and 0.75 MtCO₂/year injection rates are 22.9 and 17.8 years, respectively. The ratios of total leaked CO₂ to total injected CO₂ at 0.5 and 0.75 MtCO₂/year injection rates are 8% and 16.4%, respectively.